The coil is likely OK: they will only draw up to 4 amps at the high-end voltage of a charger. The Dyna S will normally only switch 3 amps, though. Switching more for a long time can cook them.
Tests:
Try this: plug sparkplugs into the 1-4 wires and rest the plugs against the cylinders. Then, remove the trigger wire (the one from the Dyna sensor to the coil) from the 1-4 sensor and, with the ignition turned on, ground and release this wire from the engine block. The plugs should fire each time. If not, connect a 12 volt bulb center contact (taillight bulb is OK) to that wire and ground the outside base of the bulb to the engine. It should light, if the coil is still OK. It won't light if the coil is burned open (a very rare failure, by the way).
To check the Dyna S sensor for the 1-4: these sensors are always ON until the magnet in the points cam swings by, which shuts it off while the magnet is there. (That's the equivalent of the points "opening" to make a spark.) So, connect one side of that light bulb to +12 volts (battery is OK) and ground the sensor, like when the plate is connected in the points bay, then connect the trigger wire of the sensor to the bulb's other side. This should light the bulb. Turn the points cam until the magnet is right at the sensor, and the bulb should go out. When the magnet goes away, the lamp should be back on, indicating the sensor went back ON. If this doesn't occur, the sensor is dead, either ON always or OFF always. Occasionally, they die in "half-ON" mode, which will give an always-dimly-lit bulb.
Mine died in the OFF always mode....
